AST RESEARCH, INC.

PREMIUM II 486SX/20 & 486SX/25

MODELS 202373-001 & 202373-002

Processor

80486SX/80487SX (on external CPU/Memory module)

Processor Speed

20/25MHz

Chip Set

AST

Max. Onboard DRAM

None (16MB on external CPU/Memory module)

Cache

None

BIOS

AST

Dimensions

344mm x 250mm

I/O Options

32-bit external CPU/Memory module slot

32-bit external Memory module slot (2)

bus mouse port, floppy drive interface

IDE interface, parallel port, serial port (2), SVGA port

NPU Options

4167 (on external CPU/Memory module)

CONNECTIONS

Purpose

Location

Purpose

Location

SVGA port

CN1

Front panel switches & LEDs

P5

Bus mouse port

CN2

Speaker

P6

Serial port 1 (COM1)

CN3

External battery

P8

Parallel port

CN4

IDE interface

P11

Serial port 2 (COM2)

J15

Fan power

P101

VGA pass-through

J18

32-bit external CPU/Memory module

S1

Floppy drive interface

P3

32-bit external Memory module slot

S2

Third floppy drive interface

P4

32-bit external Memory module slot

S3

USER CONFIGURABLE SETTINGS

Function

Switch SW1

Position

»

VGA port enabled

switch 1

closed

 

VGA port disabled

switch 1

open

»

Password check enabled

switch 2

open

 

Password check disabled

switch 2

closed

»

Factory configured - do not alter

switch 3

open

»

Factory configured - do not alter

switch 4

open

»

Factory configured - do not alter

switch 5

closed

»

Factory configured - do not alter

switch 6

closed

»

Monitor type select PS/2 style

switch 7

closed

 

Monitor type select AT style

switch 7

open

»

Monitor type select VGA or fixed-frequency

switch 8

open

 

Monitor type select multi-frequency

switch 8

closed

USER CONFIGURABLE SETTINGS

Function

Jumper

Position

»

Parity check enabled

E1

closed

 

Parity check disabled

E1

open

»

Factory configured - do not alter

E2

closed

Note:AST CPU/Memory module part number is 202436-001.

DRAM CONFIGURATION

Size

Bank 0

Bank 1

2MB

(2) 1M x 9

NONE

4MB

(2) 1M x 9

(2) 1M x 9

8MB

(2) 4M x 9

NONE

10MB

(2) 1M x 9

(2) 4M x 9

16MB

(2) 4M x 9

(2) 4M x 9

Notes:128KB of DRAM is reserved for System and VGA BIOS shadowing and cannot be disabled.

Up to two of the following memory boards may be installed in addition to the CPU/Memory

module: AST part numbers 202275-004, 202275-006, 202387-001, or 202387-005.